1. Field of the Invention
This invention relates generally to flight simulation and, more particularly, to a motion system for the student's station, or cockpit, of a grounded flight trainer.
2. Description of the Prior Art
Motion cue generation has been a vital aspect of flight training ever since the early LINK trainers first incorporated a bellows type motion system. Over the years, various motion systems have been developed in an attempt to simulate the transient effects produced by actual aircraft motion.
U.S. Pat. No. 2,930,144 describes a typical motion system of the prior art. As illustrated therein, limited rotational and translational movement are provided to a trainer cockpit by means of a massive structure positioned beneath the cockpit. Since flight simulators are normally installed within a building or other limited volume structure, the positioning of a massive, motion producing structure beneath the cockpit drastically reduces the space available for cockpit motion and, thereby, severely limits the available excursion range. In addition, the three degrees of motion provided by this prior art device are interdependent, which tends to detract from simulated training value because of the unrealistic limitations imposed on each degree of freedom when some other degree of freedom has been exhausted.
To overcome these disadvantages, the present inventor previously developed a Motion System for an Aircraft Flight Simulator, as described in U.S. Pat. No. 3,281,962. Employing a unique cascaded design, and a novel four-bar linkage approach, the patented motion system afforded numerous advantages over the prior art. In addition to at least four independent degrees of motion freedom throughout distances not before possible, the patented motion system also provided full vertical clearance of the cockpit with all framework and actuators outside of the cockpit vertical profile, complete independent operation of all motion actuators throughout their full range of motion, resulting in simpler computer programming and more effective simulation, and selective infinite pitch radius effects.
The present invention improves upon applicant's earlier work, retaining the significant advantages thereof, while further refining the motion system and advancing the state of the art. The instant invention improves upon the four-bar parallelogram mechanism of the prior design, by incorporating torque tubes therein. The torsional rigidity of these tubes makes unnecessary the scissor mechanism employed at the forward end of the earlier assembly to ensure lateral stability. Further, the present invention simplifies the pitch frame actuating mechanism by replacing the pair of rotary pitch actuators in the previous design, with standard linear actuators. In addition, the current invention locates the pitch pivot points behind, rather than to the side of the cockpit, thus more accurately reflecting the actual pitch characteristics of many modern day aircraft and avoiding the necessity of concurrent operation of the pitch and heave actuators to locate an "effective" pitch axis behind the cockpit. The present invention further incorporates a unique hydraulic mechanism to accomplish pitch lock, as well as other new safety features.
The three DOF motion system of the instant invention is characterized by unusual compactness, requiring a ceiling height of only 12 feet. It exhibits an extensive excursion range and provides a maximum of payload access. Furthermore, this rugged, fail-safe system realistically simulates aircraft motion effects in a highly efficient and economical manner.